JP7322416B2 - image forming device - Google Patents

Description

The present invention relates to an image forming apparatus.

An example of a conventional image forming apparatus is disclosed in Japanese Unexamined Patent Application Publication No. 2002-200012. In this image forming apparatus, a sheet on which an image is formed on one side by the image forming section is conveyed to the image forming section again through the reversing conveying path, and an image is formed on the other side.

In the reverse conveying path, one oblique feed roller and a reference guide are arranged on one end side in the width direction perpendicular to the conveying direction, and a second conveying roller pair is arranged upstream of the oblique conveying roller in the conveying direction. A second reverse conveying roller pair is arranged downstream of the oblique feed rollers in the conveying direction. Further, the sheet conveyed to the reverse conveying path is pushed against the reference guide while being obliquely conveyed by only one oblique conveying roller between the second conveying roller pair and the second reverse conveying roller pair. position is restricted.

JP 2018-172215 A

By the way, there are cases where a plurality of sheets are simultaneously processed in the image forming apparatus in order to improve the processing speed of forming images on both sides of a sheet. As a specific example, there is a case where a sheet having an image formed on one side is made to stand by in the middle of the reverse conveying path, and the next sheet is conveyed to the image forming section. In such a case, if the sheet to be put on standby is stopped while being nipped by only one skew feed roller, the sheet to be stopped rotates the skew feed roller due to frictional resistance acting on the sheet to be stopped. It can rotate around the center. As a result, there is a possibility that the leading edge of the sheet rotates away from the reference guide.

As a result, in this image forming apparatus, when the sheet is put on standby in the reverse conveying path, the sheet cannot follow the reference guide, and it becomes difficult to properly regulate the position of the sheet in the width direction. .

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus capable of properly regulating the position of a sheet in the width direction when the sheet is put on standby in a re-conveying section. do.

The image forming apparatus of the present invention includes an image forming unit that forms an image on a sheet, and a re-conveying unit that conveys the sheet on one side of which an image is formed by the image forming unit to the image forming unit again. In the forming apparatus, the re-conveying unit includes: a first conveying roller; a second conveying roller provided downstream of the first conveying roller in the conveying direction; One skew feed roller provided upstream in the transport direction from the two transport rollers and skew feeding the sheet toward one end side in the width direction perpendicular to the transport direction, comprising a first transport roller and a second transport roller. an oblique feed roller capable of obliquely feeding a sheet separated from the sheet by itself; a reference guide disposed on one end side in the width direction and regulating the position in the width direction of the sheet obliquely fed by the oblique feed roller; further comprising a control unit that controls the re-conveying unit and executes a standby operation for causing the sheet to wait in the re-conveying unit; the control unit controls the skew feeding roller and the first Stopping the skew feed roller and one of the first and second conveying rollers in a state in which the sheet is nipped between the two rollers. characterized by

In the image forming apparatus of the present invention, the skew feed rollers skew the sheet between the first conveying roller and the second conveying roller by itself, causing the sheet to follow the reference guide. Regulate position. Then, when the sheet waits in the re-conveying section, the sheet to be made to wait is nipped at two points by the skew feed roller and another roller, that is, one of the first conveying roller and the second conveying roller. Stop those rollers in a state where As a result, the behavior of the sheet nipped at two positions can be stabilized even when the sheet is subjected to frictional resistance, inertial force, or the like when the sheet is put on standby. As a result, it is possible to prevent the sheet from rotating about the oblique feed roller in a direction that does not follow the reference guide.

Therefore, in the image forming apparatus of the present invention, the position of the sheet in the width direction can be properly regulated when the sheet is put on standby in the re-conveying section. Furthermore, in this image forming apparatus, when a sheet on standby is conveyed again, the behavior of the sheet nipped at two points can be stabilized even if the sheet is subjected to frictional resistance, inertial force, or the like. can be done.

1 is a schematic cross-sectional view of an image forming apparatus of an example; FIG. FIG. 4 is a partial top view mainly showing the apparatus main body, the re-transfer unit with the cover member removed, and the connection unit with the upper beam member and the opposing member removed. FIG. 4 is a schematic cross-sectional view of the image forming apparatus in which the re-conveying unit is moved to the drawer position; 4 is a perspective view showing a re-transporting unit and a connection unit; FIG. FIG. 10 is a perspective view showing the re-transport unit with the cover member removed, and the connection unit with the upper beam member and the opposing member removed. FIG. 11 is a partial perspective view of the re-transport unit shown in positioning recesses and the like; It is a cross-sectional view of the connection unit. FIG. 10 is a schematic top view for explaining the action of the oblique feed rollers, the reference guide, etc. on the sheet; FIG. 4 is a partial schematic cross-sectional view of the image forming apparatus showing a state in which sheets are put on standby by a standby operation; FIG. 10 is a partial schematic cross-sectional view of an image forming apparatus according to a modified example, showing a state in which sheets are put on standby by a standby operation;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments embodying the present invention will be described with reference to the drawings.

(Example)
As shown in FIG. 1, the image forming apparatus 1 of the embodiment is an example of a specific aspect of the image forming apparatus of the present invention. The image forming apparatus 1 is a color laser printer that forms an image of multiple colors on the sheet SH by electrophotography.

In FIG. 1, the right side of the paper surface is defined as the front side of the device, the upper side of the paper surface is defined as the upper side of the device, and the front-rear direction and the vertical direction are displayed. Also, the left side of the device when viewed from the front side, that is, the front side of the paper surface of FIG. 1 is defined as the left side of the device. The front-rear direction, the left-right direction, and the up-down direction shown in FIG. Each component included in the image forming apparatus 1 will be described below with reference to FIG. 1 and the like.

<Structures of Apparatus Main Body, Conveying Path, Feeding Section, Image Forming Section, Discharging Section, etc.>
As shown in FIG. 1, the image forming apparatus 1 includes an apparatus main body 2, a supply section 20, an image forming section 3, and a discharge section 29. As shown in FIG.

The device main body 2 includes a housing and an internal frame (not shown) provided in the housing. A pair of side frames 90L and 90R, which are schematically shown in FIG. 2, are also internal frames. The pair of side frames 90L and 90R are arranged on the left side and the left side of the device main body 2, respectively. The pair of side frames 90L and 90R face each other in the left-right direction and extend in the front-rear direction and the up-down direction.

As shown in FIG. 1, a sheet tray accommodating portion 2A is provided inside the apparatus main body 2. As shown in FIG. The sheet tray housing portion 2A is an internal space that opens to the lower portion of the front surface of the apparatus main body 2 and is recessed toward the rear surface of the apparatus main body 2 .

A sheet tray 2C is attached to the sheet tray accommodating portion 2A. The sheet tray 2C is a substantially box-shaped body that extends substantially horizontally and has an open top. Sheets SH on which images are to be formed are accommodated in a stacked state inside the sheet tray 2C. The sheet SH is ordinary paper, an OHP sheet, cardboard, or the like.

A discharge tray 2T is provided on the upper surface of the apparatus main body 2 . A sheet SH on which an image is formed is discharged to the discharge tray 2T.

The supply unit 20, the image forming unit 3, and the discharge unit 29 are provided inside the apparatus main body 2 above the sheet tray accommodation unit 2A and the sheet tray 2C. The supply section 20, the image forming section 3 and the discharge section 29 are assembled in an internal frame (not shown).

As briefly shown in FIG. 2, the device main body 2 is provided with a control section C1 and a drive source M1. The control unit C1 is configured by a microcomputer mainly including a CPU, ROM, and RAM (not shown). The ROM stores a program for the CPU to control various operations of the image forming apparatus 1, a program for executing identification processing, and the like. The RAM is used as a storage area for temporarily recording data and signals used when the CPU executes the above programs, or as a work area for data processing. In this embodiment, the control unit C1 and the drive source M1 are arranged between the left surface of the apparatus main body 2 and the left side frame 90L. The supply unit 20, the image forming unit 3, and the discharge unit 29 are controlled by the control unit C1, and operate by transmitting the driving force of the driving source M1 via a driving force transmission unit (not shown).

As shown in FIG. 1, a transport path P1 is provided inside the apparatus main body 2 . The transport path P1 extends upward from the front end of the sheet tray 2C so as to curve into a U shape, then extends rearward substantially horizontally, and then curves upward into a U shape on the rear surface side of the apparatus main body 2 . It is a substantially S-shaped path extending in a direction to reach the discharge tray 2T.

The supply unit 20 feeds the sheets SH accommodated in the sheet tray 2C one by one to the transport path P1 by the supply roller 21, the separation roller 22, and the separation pad 22A. Then, the supply unit 20 conveys the sheet SH toward the image forming unit 3 by the pair of conveying rollers 23A and 23B and the pair of resist rollers 24A and 24B which are arranged at the U-turn portion of the conveying path P1.

A sensor 3S is provided between the pair of registration rollers 24A and 24B and the image forming section 3 on the transport path P1. As the sensor 3S, for example, a known sensor that detects the displacement of an actuator swinging in contact with the sheet SH by an optical sensor such as a photointerrupter is employed.

When the sensor 3S detects the sheet SH conveyed by the pair of registration rollers 24A and 24B, the detection result is transmitted to the controller C1. Based on the detection result, the control unit C1 determines the timing at which the sheet SH reaches the image forming unit 3, and controls the operation and stop timings of the components described above.

The image forming section 3 is of a so-called direct tandem system capable of color printing. The image forming section 3 has a process cartridge 7, a transfer belt 6, a scanner section 8, a fixing device 9, etc., which are well-known structures.

The process cartridge 7 corresponds to four color toners of black, yellow, magenta, and cyan, and is an assembly of four cartridges arranged in series along the substantially horizontal portion of the transport path P1. The process cartridge 7 has four photosensitive drums 5 corresponding to toner of each color, a developing roller (not shown), a charger, a toner container, and the like.

The transfer belt 6 is positioned below each photosensitive drum 5 across the substantially horizontal portion of the transport path P1. The transfer belt 6 circulates while sandwiching the conveyed sheet SH together with the respective photosensitive drums 5 .

The scanner unit 8 is composed of a laser light source, a polygon mirror, an fθ lens, a reflecting mirror, and the like. The scanner unit 8 irradiates each photosensitive drum 5 in the process cartridge 7 with a laser beam from above.

The fixing device 9 is provided behind the process cartridge 7 . The fixing device 9 has a heating roller 9A positioned above the transport path P1, and a pressure roller 9B pressed toward the heating roller 9A from below with the transport path P1 interposed therebetween. The fixing device 9 heats and presses the sheet SH passing under the process cartridge 7 with a heating roller 9A and a pressure roller 9B.

A sensor 9S is provided behind the heating roller 9A and the pressure roller 9B in the transport path P1. The configuration of the sensor 9S is similar to that of the sensor 3S.

When the sensor 9S detects the sheet SH passing through the fixing device 9, the detection result is transmitted to the control section C1. Based on the detection result, the control unit C1 determines the timing at which the sheet SH leaves the image forming unit 3, and controls the operation and stop timings of the components described above.

The discharge section 29 has a discharge roller 29A, a discharge pinch roller 29B and a flapper 29F. The discharge roller 29A and the discharge pinch roller 29B are positioned on the most downstream side of the transport path P1.

The flapper 29F is provided at a position behind and below the ejection roller 29A and the ejection pinch roller 29B inside the apparatus main body 2 . The flapper 29F is swingably supported by a frame member (not shown) at its lower end, and is swingable between a position indicated by a solid line in FIG. 1 and a position indicated by a two-dot chain line in FIG.

The flapper 29F is held at the position indicated by the two-dot chain line in FIG. 1 by a spring (not shown). When the sheet SH is conveyed along the conveying path P1 toward the discharge tray 2T, the flapper 29F is pushed by the sheet SH and swings to the position indicated by the solid line in FIG. 1, thereby preventing the sheet SH from being conveyed. It's not supposed to.

The image forming section 3 forms an image on the sheet SH conveyed along the conveying path P1 as follows. That is, the surface of each photosensitive drum 5 is uniformly positively charged by the charger as it rotates, and then exposed by high-speed scanning of the laser beam emitted from the scanner unit 8 . As a result, an electrostatic latent image corresponding to the image to be formed on the sheet SH is formed on the surface of each photosensitive drum 5 . Next, the toner is supplied from the toner container to the surface of each photosensitive drum 5 corresponding to the electrostatic latent image. When the sheet SH is accommodated in the sheet tray 2C, one surface SH1 of the sheet SH faces downward. When the sheet SH is conveyed along the conveying path P1 and passes through the image forming portion 3, one surface SH1 of the sheet SH faces upward and faces the photosensitive drum 5. FIG. Therefore, the toner carried on the surface of each photosensitive drum 5 is transferred to one surface SH1 of the sheet SH, and is heated and pressurized by the fixing device 9. FIG. As a result, the toner is fixed on the sheet SH.

The sheet SH that has passed through the fixing device 9 is nipped by the discharge roller 29A and the discharge pinch roller 29B of the discharge section 29, and is discharged to the discharge tray 2T by the forward rotation of the discharge roller 29A.

<Schematic configuration of re-transport route, re-transport unit, etc.>
In the apparatus main body 2, a re-conveying path P2 is provided for forming an image also on the surface of the sheet SH opposite to the one surface SH1. The re-conveying path P2 extends downward along the rear surface of the apparatus main body 2 from the discharge section 29, then changes direction, extends forward and substantially horizontally below the sheet tray 2C, and further turns toward the front side of the apparatus main body 2. It is a path that extends upward and merges at a position between the separation roller 22 and the pair of transport rollers 23A and 23B on the transport path P1.

The conveying direction of the sheet SH conveyed along the re-conveying path P2 is assumed to be the conveying direction D1. The conveying direction D1 changes from downward to forward and substantially horizontally, and then changes upward. Alternatively, the width direction of the sheet SH conveyed by the re-conveying path P2 is the left-right direction.

The discharge unit 29 also serves as a reversing mechanism that reverses the sheet SH conveyed along the conveying path P1 and sends it out to the re-conveying path P2. More specifically, after the sensor 9S stops detecting the trailing edge of the sheet SH while the sheet SH is sandwiched between the ejection rollers 29A and the ejection pinch rollers 29B and ejected toward the ejection tray 2T, the control is performed at a predetermined timing. The section C1 switches the discharge roller 29A from forward rotation to reverse rotation. The predetermined timing is set after the trailing edge of the sheet SH passes the flapper 29F and the flapper 29F swings to the position indicated by the two-dot chain line in FIG. As a result, the sheet SH is sent out to the re-conveying path P2 by the counter-rotating discharge roller 29A, the discharge pinch roller 29B, and the flapper 29F located at the position indicated by the two-dot chain line in FIG.

The image forming apparatus 1 includes a re-conveying section 10 . 1 to 6 and 8; a connection unit 200 shown in FIGS. 1 to 5 and 8; 1 and a return guide 69 shown in FIG. The re-transport unit 100 is an example of the "first unit" of the present invention. The connection unit 200 is an example of the "second unit" of the present invention.

The re-conveying section 10 conveys the sheet SH reversed by the discharging section 29 along the re-conveying path P2 by the reversing guide 61, the re-conveying unit 100, the connection unit 200, and the return guide 69, and returns it to the image forming section 3. return. After an image is formed on the surface of the sheet SH opposite to the one surface SH1 in the image forming portion 3, the sheet SH is discharged onto the discharge tray 2T. A specific configuration of the re-conveying section 10 will be described in detail below.

<Structure of Reversing Guide, First Conveying Roller, etc.>
The reversing guide 61 defines a portion extending downward along the rear surface of the apparatus main body 2 from the discharge section 29 on the re-conveyance path P2. A first conveying roller 11 and a pinch roller 11P are provided at an intermediate portion of the reversing guide 61 in the conveying direction D1.

The first transport roller 11 is a direct feed roller that rotates around a first axis X11 parallel to the width direction. The pinch roller 11</b>P is pressed toward the first conveying roller 11 . As shown in FIG. 2, the first conveying roller 11 and the pinch roller 11P are elongated in the left-right direction so as to ensure a large nipping length of the sheet SH in the width direction.

A third transmission portion G3 is provided on the left side frame 90L. The third transmission portion G3 is configured including a plurality of gears, a transmission shaft, and the like, although it is simply shown, and transmits the driving force from the driving source M1 to the first conveying rollers 11 . In addition, the third transmission portion G3 may include a clutch capable of switching transmission and interruption of the driving force from the driving source M1 depending on the situation.

As shown in FIG. 1 , the first conveying roller 11 and the pinch roller 11 P nip the sheet SH reversed by the discharging section 29 and convey it toward the re-conveying unit 100 .

<Composition of return guide>
The return guide 69 is provided inside the front end portion of the sheet tray 2C. The return guide 69 is an example of the "second curved portion" of the present invention. More specifically, an extension 2C1 is formed at the front end of the sheet tray 2C. The extending portion 2C1 extends downward from the bottom surface 2C2 of the sheet tray 2C and approaches the bottom wall 2D.

The entrance of the return guide 69 is open on the rear facing surface of the extension 2C1. The outlet of the return guide 69 is open on the upward facing surface of the front end of the sheet tray 2C. The return guide 69 changes its orientation from forward to upward on the front side of the apparatus main body 2 in the re-transport path P2, and defines a portion that extends upward and merges with the transport path P1.

The third re-conveying path P23 is a conveying path through which the sheet passes within the return guide 69, and is a portion of the re-conveying path P2 defined by the return guide 69 that turns from the forward direction and merges with the conveying path P1. be. The upstream end of the third re-transport path P23 in the transport direction D1 is positioned at the extension 2C1.

<Structure of Re-Conveying Unit, Skewed Feed Roller, Drive Roller, etc.>
The re-conveying unit 100 extends horizontally below the sheet tray 2C. The reconveyance unit 100 defines a curved portion that changes its direction from downward to forward in the reconveyance path P2 and a part of a portion that extends substantially horizontally forward. A part of the substantially horizontally extending portion of the re-transport path P2 defined by the re-transport unit 100 is defined as a first re-transport path P21.

The re-conveying unit 100 is movable between an accommodation position where it is accommodated in the apparatus main body 2 as shown in FIG. 1 and a drawer position where it is pulled out rearward from the accommodation position as shown in FIG. In this embodiment, the re-conveying unit 100 is entirely positioned outside the apparatus main body 2 at the pulled-out position. Although the re-conveying unit 100 is arranged below the image forming apparatus 1 in FIG.

When the sheet SH is jammed in the re-conveying path P2, the user can remove the jammed sheet SH by pulling out the re-conveying unit 100 from the storage position to the drawer position.

As shown in FIG. 4, the re-conveying unit 100 has a first guide member 110 and a cover member 120. As shown in FIG. The re-conveying unit 100 shown in FIGS. 2 and 5 is in a state where the cover member 120 is removed.

As shown in FIGS. 2, 4 and 5, guide ribs 119L and 119R are formed on the left and right side surfaces of the first guide member 110. As shown in FIGS. The guide ribs 119L, 119 protrude outward in the width direction from the left and right side surfaces of the first guide member 110 and extend in the front-rear direction.

The guide ribs 119L, 119 of the reconveying unit 100 are guided by guide rails (not shown) formed on the pair of side frames 90L, 90R shown in FIG. 3 smoothly moves to and from the drawn-out position. The re-transport unit 100 shown in FIG. 2 is also in the stowed position.

As shown in FIGS. 1, 2 and 5, the upper surface of the first guide member 110 is formed with a curved conveying surface 116G and a first conveying surface 110G. The curved conveying surface 116G is an example of the "first curved portion" of the present invention. The first conveying surface 110G and a second conveying surface 210G, which will be described later, are examples of the "horizontal portion" of the present invention.

The curved conveying surface 116G is located on the rear end side of the first guide member 110, and defines from below a curved portion of the reconveying path P2 that changes direction from downward to forward. The curved conveying surface 116G is a substantially curved surface formed by leading edges of a plurality of ribs.

As shown in FIGS. 2 and 5, a side chute 118 is attached to the left end of the curved conveying surface 116G. The side chute 118 guides the left edge of the sheet SH guided by the curved conveying surface 116G.

The first conveying surface 110</b>G connects to the downstream end of the curved conveying surface 116</b>G in the conveying direction D<b>1 and extends substantially horizontally to the front end of the first guide member 110 . The first transport surface 110G defines the first retransport path P21 from below. The first conveying surface 110G is a substantially flat surface formed by the tip edges of a plurality of ribs.

As shown in FIG. 2, a virtual line extending in the transport direction D1 passing through the widthwise center of the first transport surface 110G is defined as a center line LC1. A left reference line LL1 is an imaginary line extending parallel to the center line LC1 on the left edge side of the first conveying surface 110G. A virtual line extending parallel to the center line LC1 on the right edge side of the first conveying surface 110G is defined as a right reference line LR1.

The widthwise distance between the left reference line LL1 and the right reference line LR1 is set equal to the widthwise length of the sheet SH conveyed on the first conveying surface 110G. The distance in the width direction between the center line LC1 and the left reference line LL1 and the distance in the width direction between the center line LC1 and the right reference line LR1 are set equal.

That is, by aligning the left edge of the sheet SH transported on the first transport surface 110G with the left reference line LL1, the widthwise center of the sheet SH can be aligned with the center line LC1. The center line LC1 also coincides with the center of the image forming section 3 in the width direction.

As shown in FIGS. 2 and 5, the reference guide 30 is arranged on one end side in the width direction of the first conveying surface 110G of the first guide member 110, that is, on the left end side. The reference guide 30 is a sheet metal member having a substantially C-shaped cross section and having a lower wall 31 , a reference wall 32 and an upper wall 33 . The reference guide 30 is assembled to the first guide member 110 in a state in which the lower wall 31 is flush with the first conveying surface 110G and the reference wall 32 is positioned on the left reference line LL1 and extends along the conveying direction D1. It is

As shown in FIG. 8, the rear end side of the reference wall 32 of the reference guide 30 is bent so as to deviate leftward from the left reference line LL1 toward the upstream side in the transport direction D1. The front end of the side wall 118A of the side chute 118 is adjacent to the rear end of the reference wall 32 from the right and touches the left reference line LL1. The side wall 118A is inclined so as to deviate leftward from the left reference line LL1 toward the upstream side in the transport direction D1. A cylindrical pin may be arranged at the front end of the side wall 118A of the side chute 118 .

As shown in FIG. 4, the cover member 120 is a sheet metal member and covers substantially the entire first conveying surface 110G of the first guide member 110 from above. An oblique feed roller 13P is held on the rear end side and left end side of the cover member 120 .

In FIGS. 2 and 5, the oblique feed roller 13P is shown at the same position as in FIG. 4, and the driving roller 13 shown in FIG. 1 is arranged and hidden below the oblique feed roller 13P. As shown in FIG. 2, the oblique feed roller 13P is rotatable around a first axis X13P that is inclined with respect to the width direction. The first axis X13P is inclined such that the right end of the oblique feed roller 13P is shifted forward from the left end of the oblique feed roller 13P.

As shown in FIG. 1, the drive roller 13 is rotatably supported by the first guide member 110 . The drive roller 13 is in contact with the oblique feed roller 13P from below with the first re-conveyance path P21 interposed therebetween.

As shown in FIG. 5 , the left end of the rotation shaft 13</b>S extending in the left-right direction of the driving roller 13 protrudes from the left side surface of the first guide member 110 . A spur gear 13G is fixed to the left end of the rotating shaft 13S.

As shown in FIG. 2, the left side frame 90L is provided with a first transmission portion G1. The first transmission part G1 is configured including a plurality of gears, a transmission shaft, etc., although it is simply shown, and transmits the driving force from the driving source M1 via the spur gear 13G, the rotating shaft 13S and the driving roller 13. is transmitted to the oblique feed roller 13P. Note that the first transmission portion G1 may include a clutch capable of switching transmission and cutoff of the driving force from the driving source M1 depending on the situation.

Although not shown, the first transmission portion G1 has a spur gear that meshes with the spur gear 13G from the front. When the re-conveying unit 100 is pulled out backward from the housed position shown in FIG. 1 and moves to the drawn-out position shown in FIG. The spur gear 13G meshes with the spur gear 13G when it is pushed forward from the drawn position to move to the storage position.

The oblique feed roller 13</b>P and the drive roller 13 nip the sheet SH transported by the first transport roller 11 and the pinch roller 11</b>P on the first transport surface 110</b>G and transport the sheet SH toward the connection unit 200 . At this time, the oblique feed roller 13P driven and rotated by the drive roller 13 obliquely feeds the sheet SH on the first conveying surface 110G toward the reference wall 32 of the reference guide 30 due to the inclination of the first axis X13P.

As shown in FIG. 6, the front end surface of the first guide member 110 of the re-conveying unit 100 is provided with two positioning recesses 110K. Each positioning recess 110K is a substantially rectangular hole recessed rearward from the front end surface of the first guide member 110, and is spaced apart from each other in the width direction.

Further, an actuator pressing portion 110J is formed so as to protrude forward at the center of the front end surface of the first guide member 110 in the width direction.

<Structure of Connection Unit, Second Conveying Roller, Actuator, etc.>
As shown in FIG. 1, the connection unit 200 extends horizontally below the sheet tray 2C. Also, the connection unit 200 is arranged side by side with the re-conveying unit 100 and the extending portion 2C1 of the sheet tray 2C in the front-rear direction.

The connection unit 200 defines a portion extending substantially horizontally forward in the re-transport path P2. A portion of the re-transport path P2 extending substantially horizontally forward is referred to as a second re-transport path P22.

The second re-transport path P22 is connected to the downstream end of the first re-transport path P21 in the transport direction D1 and the upstream end of the third re-transport path P23 in the transport direction D1. That is, the re-conveying path P2 has a first re-conveying path P21, a second re-conveying path P22, and a third re-conveying path P23 in order of the conveying direction D1 of the sheet SH.

By dividing the substantially horizontally extending portion of the re-conveying path P2 into the first re-conveying path P21 and the second re-conveying path P22, as shown in FIG. The length is somewhat shorter than the length of the re-conveyed sheet SH in the conveying direction D1.

As shown in FIGS. 2, 4, 5 and 7, the connection unit 200 includes a lower beam member 230, a second guide member 210, a facing member 220 and an upper beam member 240. As shown in FIG. The lower beam member 230, the second guide member 210, the opposing member 220 and the upper beam member 240 are connected to each other by a plurality of fastening screws (not shown).

The lower beam member 230 is arranged at the bottom of the connection unit 200 . The lower beam member 230 is a sheet metal member and extends in the left-right direction. As shown in FIG. 2, the left and right ends of the lower beam member 230 are connected to a pair of side frames 90L and 90R. Further, as shown in FIG. 5, the left and right ends of the lower beam member 230 are positioned by positioning pins 90P provided to project upward from the pair of side frames 90L and 90R.

As shown in FIGS. 5 and 7, the second guide member 210 is a resin molded product and is supported from below by a lower beam member 230. As shown in FIGS. A second transport surface 210G is formed on the upper surface of the second guide member 210 . The second transport surface 210G extends substantially horizontally from the rear end to the front end of the top surface of the second guide member 210 . The second transport surface 210G defines the second retransport path P22 from below. As shown in FIG. 2, the center line LC1 passes through the widthwise center of the second transport surface 210G.

The second conveying surface 210G and the above-described first conveying surface 110G are examples of the "horizontal portion" of the present invention. As shown in FIG. 1, the first conveying surface 110G and the second conveying surface 210G feed the sheet so as to pass through the oblique feed roller 13P and reach the second conveying roller 12 while maintaining the conveying direction D1 substantially horizontally. Guide SH.

As shown in FIGS. 5 and 7, the second guide member 210 is provided with two positioning protrusions 210K. Each positioning projection 210K protrudes rearward from the rear surface of the second guide member 210 toward the first guide member 110 of the re-conveying unit 100 . Each positioning protrusion 210K is arranged at a position aligned with each positioning recess 110K of the first guide member 110, and is spaced apart from each other in the width direction.

Each positioning protrusion 210K is fitted into each positioning recess 110K while the re-transfer unit 100 is in the accommodation position. As a result, the re-conveying unit 100 is positioned with respect to the connection unit 200 and the apparatus main body 2 as shown in FIG.

As shown in FIG. 7 , the opposing member 220 is a resin molded product and is arranged above the second guide member 210 . The facing member 220 faces the second conveying surface 210G with a gap therebetween. A guide surface 220G is formed on the lower surface of the opposing member 220 . The guide surface 220G defines the second re-conveyance path P22 from above.

As shown in FIGS. 4 and 7 , the upper beam member 240 is arranged on the top of the connection unit 200 . The upper beam member 240 is a sheet metal member and extends in the left-right direction. The upper beam member 240 reinforces the facing member 220 from above.

As shown in FIGS. 2, 5 and 7, two second transport rollers 12 are provided on the second guide member 210 side of the connection unit 200 .

Each of the second transport rollers 12 is rotatable around a second axis X12 parallel to the width direction with its upper end side exposed from the second transport surface 210G. As shown in FIG. 2, the second conveying rollers 12 are arranged so as to be equidistant from each other on the left and right sides of the center line LC1.

As shown in FIG. 7, two pinch rollers 12P are provided on the facing member 220 side of the connection unit 200. As shown in FIG. Each pinch roller 12P is held by the facing member 220 with its lower end side exposed from the guide surface 220G. Each pinch roller 12P is pressed toward each second transport roller 12 by a pressing member (not shown) arranged between the upper beam member 240 and the facing member 220 .

As shown in FIG. 5 , the left end of the rotating shaft 12</b>S extending in the left-right direction of each second conveying roller 12 protrudes from the left side surface of the second guide member 210 . A spur gear 12G is fixed to the left end of the rotating shaft 12S.

As shown in FIG. 2, the left side frame 90L is provided with a second transmission portion G2. The second transmission portion G2 is configured including a plurality of gears, a transmission shaft, etc., although it is simply shown, and transmits the driving force from the driving source M1 via the spur gear 12G and the rotation shaft 12S to each second transmission portion G2. It is transmitted to the conveying roller 12 . The second transmission portion G2 may include a clutch capable of switching transmission and cutoff of the driving force from the driving source M1 depending on the situation.

Each of the second conveying rollers 12 and each of the pinch rollers 12P nips the sheet SH skew-fed by the skew-feeding roller 13P and the driving roller 13 on the second conveying surface 210G to define the third re-conveying path P23. It is conveyed toward the guide 69.

As shown in FIG. 1, the length of the re-conveying path P2 from the first conveying roller 12 to each of the second conveying rollers 12 is set larger than the length of the re-conveyed sheet SH in the conveying direction D1. Therefore, the skew feed roller 13</b>P and the drive roller 13 can skew the sheet SH separated from the first transport roller 11 and the second transport roller 12 independently.

As shown in FIGS. 2, 5, and 7, an actuator 70 is provided on the second guide member 210 side of the connection unit 200 to detect the presence or absence of the sheet SH passing over the second conveying surface 210G. The actuator 70 is arranged on the rear end side of the second conveying surface 210G, and can swing about a swing axis X70 parallel to the width direction.

As shown in FIG. 2 , the actuator 70 is provided downstream of the skew feed roller 13</b>P in the transport direction D<b>1 and upstream of the second transport roller 12 in the transport direction D<b>1 . Further, the actuator 70 is arranged on the centerline LC1.

As shown in FIG. 7, a torsion coil spring 70T is provided on the second guide member 210 side of the connection unit 200 . The torsion coil spring 70T exerts a biasing force that biases the actuator 70 upstream in the transport direction D1.

The actuator 70 (70A) shown in FIGS. 2, 7 and 8 is in a first standby position protruding upward from the second conveying surface 210G. As shown in FIG. 7, the upper end of the actuator 70 (70A) at the first standby position is located above the guide surface 220G.

The actuator 70 (70B) shown in FIGS. 5 and 7 is swung from the first standby position to the upstream side in the transport direction D1 by the biasing force of the torsion coil spring 70T and held at the second standby position. ing.

The actuator 70 (70C) shown in FIG. 7 is pushed by the sheet SH passing over the second conveying surface 210G and moves from the first standby position to the downstream side in the conveying direction D1 against the biasing force of the torsion coil spring 70T. It is shown in a collapsed passing position. The actuator 70 (70C) at the passing position retreats below the second conveying surface 210G to allow the passage of the sheet SH.

As shown in FIG. 2, the actuator pressing portion 110J of the first guide member 110 pushes the actuator 70 forward by moving the re-conveying unit 100 from the drawn-out position to the housed position. As a result, the actuator 70 (70A) is held at the first standby position.

On the other hand, as shown in FIG. 5, when the re-conveying unit 100 moves from the housed position to the drawn-out position, the actuator pressing portion 110J of the first guide member 110 is separated rearward from the actuator 70, and the actuator 70 is moved. It swings from the first standby position to the upstream side in the transport direction D1. As a result, the actuator 70 (70B) is held at the second standby position.

As shown in FIGS. 2 and 5 , the swing shaft 70</b>S extending in the left-right direction of the actuator 70 has its left end protruding from the left side surface of the second guide member 210 . A detected portion 70Q is formed at the left end of the swing shaft 70S. The detected portion 70Q is a plate-like piece that protrudes in the same direction as the direction in which the actuator 70 protrudes, which is the outward radial direction of the swing axis X70.

As briefly shown in FIG. 2, a photointerrupter 70U is provided at a position corresponding to the detected portion 70Q on the left side frame 90L. The photointerrupter 70U detects that the actuator 70 is at the first standby position when the optical path from the light emitting section to the light receiving section is interrupted by the detected section 70Q, and transmits an ON signal to the control section C1. On the other hand, the photointerrupter 70U detects that the actuator 70 is not at the first standby position by opening the optical path by the detected portion 70Q, and transmits an OFF signal to the control portion C1.

When the controller C1 receives an ON signal from the photointerrupter 70U while the driving source M1 is not operating, the controller C1 determines that the re-conveyance unit 100 is at the accommodation position, while receiving an OFF signal from the photointerrupter 70U. Then, it is determined that the re-conveying unit 100 is not at the accommodation position.

Further, when the controller C1 receives the ON signal from the photointerrupter 70U in a state in which the driving source M1 is operated to re-convey the sheet SH, the actuator 70 is at the first standby position and the second conveying surface is set. On the other hand, when the OFF signal is received from the photointerrupter 70U, it is determined that the actuator 70 is at the passing position and the sheet SH is present on the second conveying surface 210G.

That is, the actuator 70 serves both to detect the presence or absence of the sheet SH on the second conveying surface 210</b>G and to detect the position of the re-conveying unit 100 .

<Action of Skewed Feeding Roller, Reference Guide, etc. on Re-Conveyed Sheet>
The sheet SH (SHa) shown in FIG. 8 is further conveyed in the conveying direction D1 from a state in which it is nipped between the first conveying roller 11 and the oblique conveying roller 13, which are direct feed rollers, and the trailing edge of the sheet SH reaches the first conveying roller. 11, and the skew feed roller 13 begins to skew feed independently. Note that the sheet SH is skew-fed singly means that the trailing edge of the sheet SH is located downstream of the first transport roller 11 in the transport direction D1, and the front edge of the sheet SH is transported further than the second transport roller 12. It is a state in which the sheet SH is obliquely fed only by the oblique feeding roller 13 in a state positioned on the upstream side in the direction D1. Further, the sheet SH (SHa) shown in FIG. 8 is shifted in the width direction and inclined with respect to the center line LC1 as an example.

The oblique feed roller 13 obliquely feeds such a sheet SH (SHa) toward the reference wall 32 of the reference guide 30 . As a result, the left edge of the sheet SH (SHa) contacts the front end of the side wall 118A of the side chute 118 while being inclined with respect to the left reference line LL1.

Then, the oblique feed roller 13 rotates the sheet SH (SHa) on the first transport surface 110G clockwise in FIG. 8 with the front end of the side wall 118A of the side chute 118 as the center of rotation. As a result, the left edge of the sheet SH (SHb) follows the reference wall 32 of the reference guide 30, like the sheet SH (SHb) shown in FIG.

As a result, the re-conveying unit 10 aligns the left edge of the sheet SH (SHb) with the left reference line LL1, and aligns the center of the sheet SH (SHb) in the width direction with the center line LC1. properly regulate the position of

Further, when the skew feed roller 13 alone conveys the sheet SH (SHb) in the conveying direction D1, the sheet SH (SHb) pushes the actuator 70 (70A) at the first standby position, causing the actuator 70 to swing to the passing position. move. As a result, the controller C1 determines that there is a sheet SH on the second conveying surface 210G, and uses it for various timing controls.

Then, like the sheet SH (SHc) shown in FIG. 8, it is nipped between the oblique feed roller 13 and the two second conveying rollers 12, which are the direct feeding rollers, so that it is difficult to change its posture. It is conveyed toward the re-conveyance path P23. The sheet SH (SHc) shown in FIG. 9 is in the same state as the sheet SH (SHc) shown in FIG.

<Details of the standby operation for waiting the sheet at the re-conveying unit>
The image forming apparatus 1 may process a plurality of sheets SH at the same time in order to increase the processing speed of forming images on both sides of the sheet SH. As a specific example, the sheet SH having an image formed on one side SH1 may be made to wait in the middle of the re-conveyance path P2 and the next sheet SH may be conveyed to the image forming portion 3 .

In this case, the control unit C1 controls the re-conveying unit 10 by using the detection of the presence or absence of the sheet SH on the second conveying surface 210G by the actuator 70, and the predetermined time elapses from the timing when the actuator 70 falls to the passing position. After that, the standby operation of waiting the sheet SH in the re-conveying unit 10 is executed.

Here, in this embodiment, when the standby operation is executed, the control unit C1 controls the first transmission unit G1 and the second transmission unit G2 so that the seat SH (SHc) shown in FIGS. , the skew feed roller 13P and the second transport roller 12 are stopped in a state where the sheet SH is nipped by the two rollers, the skew feed roller 13P and the second transport roller 12. . As a result, the sheet SH (SHc) to be put on standby stops on the first conveying surface 110G and the second conveying surface 210G.

Then, after a predetermined waiting time has elapsed, the control section C1 controls the first transmission section G1 and the second transmission section G2 to operate the two rollers, the oblique feeding roller 13P and the second conveying roller 12. The sheet SH (SHc) that has been rotated and waited is conveyed toward the third re-conveyance path P23.

By such a standby operation, the image forming apparatus 1 can preferably perform the operation of simultaneously processing a plurality of sheets SH within the image forming apparatus 1 .

<Effect>
In the image forming apparatus 1 of the embodiment, the skew feeding roller 13P singly feeds the sheet SH between the first conveying roller 11 and the second conveying roller 12, such as the sheet SH (SHa, SHb) shown in FIG. The position of the sheet SH in the width direction is regulated by obliquely feeding the sheet SH and causing the sheet SH to follow the reference guide 30 .

Then, like the sheet SH (SHc) shown in FIGS. 8 and 9, when the sheet SH waits in the re-conveyance unit 10, the skew feed roller 13P and another roller, that is, the second conveying roller 12 These rollers are stopped in a state in which the sheet SH (SHc) to be put on standby is nipped at two positions.

Here, as shown in FIG. 8, when the sheet SH is put on standby, frictional resistance, inertial force, or the like may act on the sheet SH. easy. This force F1 tends to act toward the upstream side in the transport direction D1 at a position opposite to the reference guide 30 in the width direction.

In this respect, in the image forming apparatus 1, the behavior of the sheet SH is stabilized by nipping the sheet SH (SHc) to be put on standby at two positions between the oblique feed roller 13P and the second conveying roller 12. be able to. As a result, it is possible to prevent the sheet SH from rotating about the oblique feed roller 13P in a direction that does not follow the reference guide 30, that is, counterclockwise in FIG.

Therefore, in the image forming apparatus 1 of the embodiment, when the sheet SH is made to wait in the re-conveying section 10, the position of the sheet SH in the width direction can be properly regulated.

Furthermore, in the image forming apparatus 1, when the sheet SH that has been on standby is transported again, frictional resistance, inertial force, or the like may act on the sheet SH. force F2 is likely to act. This force F2 also tends to act toward the upstream side in the transport direction D1 at a position opposite to the reference guide 30 in the width direction. In this case as well, the behavior when the sheet SH (SHc) nipped at two locations is conveyed toward the third re-conveying path P23 can be stabilized.

In the image forming apparatus 1, as shown in FIG. 2, the first conveying roller 11 and the second conveying roller 12, which are direct feed rollers, allow the sheet SH to be conveyed in a section where the skew feed roller 13P alone does not skew the sheet SH. SH can be conveyed straight.

Further, in the image forming apparatus 1, the control unit C1 causes the sheet SH obliquely fed only by the oblique feeding roller 13P to pass through the second conveying roller 12, which is a direct feeding roller, like the sheet SH (SHc) shown in FIG. After the sheet SH is nipped and the behavior is stabilized, the standby operation is performed on the sheet SH, so the behavior of the sheet SH to be made to wait can be made more stable.

Further, in the image forming apparatus 1, as shown in FIG. 8, it is provided downstream of the skew feeding roller 13P in the re-conveying section 10 in the conveying direction D1 and upstream of the second conveying roller 12 in the conveying direction D1. When the actuator 70 abuts against the sheet SH, a reaction force acts on the sheet SH from the actuator 70, and the behavior of the sheet SH may be destabilized. In this respect, the controller C1 performs the standby operation as described above, thereby suppressing the influence of the actuator 70 on the behavior of the sheet SH.

Further, in the image forming apparatus 1, as shown in FIG. 9, the frictional resistance acting on the sheet SH flat on the first conveying surface 110G and the second conveying surface 210G is the curved conveying surface 116G or the It is smaller than the frictional resistance acting on the sheet SH that is curved by the return guide 69 . Therefore, by stopping the sheet SH on the first conveying surface 110G and the second conveying surface 210G when the control unit C1 performs the standby operation, the forces F1 and F2 shown in FIG. The behavior of the seat SH can be made more stable.

Further, in the image forming apparatus 1, as shown in FIG. 3, by moving the re-conveying unit 100 to the drawer position, it is possible to easily remove the sheet SH jammed in the re-conveying section 10 and the like.

Furthermore, in this image forming apparatus 1, even if the re-conveying unit 100 is moved to the drawn-out position, the actuator 70 remains inside the apparatus main body 2, so damage to the actuator 70 can be suppressed. Moreover, regardless of the movement between the accommodation position and the drawer position of the reconveyance unit 100, as shown in FIG. Since the positional relationship with the photointerrupter 70U can be maintained constant, the presence or absence of the sheet SH can be detected with high accuracy.

<Modification>
As in the modified example shown in FIG. 10, when executing the standby operation, the control unit C1 performs the first conveying operation while the sheet SH (SHd) is nipped between the first conveying roller 11 and the skew feeding roller 13P. The roller 11 and the oblique feed roller 13P may be stopped. Also in this case, similarly to the image forming apparatus 1 of the embodiment, the problem that the sheet SH (SHd) to be put on standby is prevented from rotating in a direction not following the reference guide 30 about the skew feed roller 13P is suppressed. can. As a result, even in the modified example, when the sheet SH is put on standby in the re-conveying section 10, the position of the sheet SH in the width direction can be properly regulated.

Although the present invention has been described above with reference to the embodiments, it goes without saying that the present invention is not limited to the above embodiments, and can be modified and applied without departing from the scope of the invention.

INDUSTRIAL APPLICABILITY The present invention can be used, for example, in an image forming apparatus, a multifunction machine, or the like.

REFERENCE SIGNS LIST 1 image forming apparatus SH sheet 3 image forming unit SH1 one surface of sheet 10 re-conveying unit 11 first conveying roller D1 conveying direction 12 second conveying roller 13P oblique feeding Roller 30 Reference guide C1 Control unit X11 First axis X12 Second axis 70 Actuator 2C Sheet tray 116G First curved portion (curved conveying surface)
110G, 210G...horizontal part (110G...first conveying surface, 210G...second conveying surface)
69... Second bending portion (return guide), 2... Apparatus main body 100... First unit (re-conveying unit)
200...Second unit (connection unit)

Claims (5)

an image forming unit that forms an image on a sheet;
a re-conveying unit that conveys the sheet on one side of which an image has been formed by the image forming unit to the image forming unit again;
An image forming apparatus comprising
The re-conveyance unit
a first conveying roller;
a second transport roller provided downstream in the transport direction from the first transport roller;
It is provided downstream in the conveying direction from the first conveying roller and upstream in the conveying direction from the second conveying roller, and obliquely feeds the sheet toward one end side in the width direction orthogonal to the conveying direction. a single skew feed roller capable of skew feeding a sheet separated from the first conveying roller and the second conveying roller;
a reference guide arranged on the one end side in the width direction and regulating the position in the width direction of the sheet obliquely fed by the oblique feeding roller;
an actuator provided downstream in the conveying direction of the oblique feed roller and upstream in the conveying direction of the second conveying roller, capable of coming into contact with a sheet, and detecting the presence or absence of the sheet;
has
further comprising a control unit that controls the re-conveying unit and performs a standby operation for causing the sheet to wait in the re-conveying unit;
When executing the standby operation, the control unit conveys the sheet until the leading edge of the sheet passes through a nip position of the second conveying roller after the leading edge of the sheet is detected by the actuator. and the second conveying roller, wherein the skew feed roller and the second conveying roller are stopped in a state where the sheet is nipped by the second conveying roller. The first transport roller is a direct feed roller that rotates around a first axis parallel to the width direction,
2. The image forming apparatus according to claim 1, wherein said second conveying roller is a direct feed roller rotating around a second axis parallel to said width direction. a sheet tray provided below the image forming unit and containing sheets to be supplied to the image forming unit;
The re-conveyance unit
a first curving portion disposed upstream in the conveying direction of the oblique feed roller and guiding the sheet by curving so as to change the conveying direction from downward to substantially horizontal;
It is connected to the end of the first curved portion on the downstream side in the conveying direction at a position below the sheet tray, and passes through the oblique feed roller while maintaining the conveying direction in a substantially horizontal direction. 2 a horizontal portion for guiding the sheet to reach the conveying roller;
a second curved portion that is connected to an end portion of the horizontal portion on the downstream side in the conveying direction and guides the sheet by curving so as to change the conveying direction from the substantially horizontal direction upward;
has
3. The image forming apparatus according to claim 1, wherein, when executing the standby operation, the control section stops the sheet to be made to stand by at the horizontal portion. an apparatus main body that accommodates the image forming unit, the re-conveying unit, and the sheet tray;
The re-conveyance unit
a first unit that includes the oblique feed roller and a part of the horizontal portion and is movable between a housed position housed in the apparatus main body and a drawn position pulled out from the housed position;
a second unit including the second conveying roller and the other portion of the horizontal portion;
4. The image forming apparatus according to claim 3 , comprising: 5. The image forming apparatus according to claim 4 , wherein said second unit includes said actuator.

Images